This invention relates to a process for the preparation of hydroxyalkylamides and, more particularly, to such a process which provides high conversion rates and low by-product formation.
A known process for producing a hydroxyalkylamide involves reacting an alkyl ester and an alkanolamine in the presence of solvent and catalyst with removal of low boiling alcohol by-product to push the reaction to completion. Besides low boiling alcohol, this process usually results in the production of one or more additional by-products, e.g., cyclic products, alkyl esters, amide esters, and the like. A typical process of this type involves reacting a fatty acid ester and an N-alkylglucamine in accordance with the reaction: EQU R'COOCH.sub.3 +CH.sub.3 NHR".revreaction.R'CONCH.sub.3 R"+CH.sub.3 OH
wherein R' is an alkyl group of from about 5 to about 31 carbon atoms and R" is a polyhydroxy-substituted saturated hydrocarbon group of from about 5 to about 8 carbon atoms. The fatty acid ester reactant is typically prepared by reacting an alcohol with a fatty acid. The N-alkylglucamine reactant is typically prepared by reacting an alkyl amine with a polyhydroxy reducing sugar. The hydroxyalkylamide product is recovered from the reaction mixture by stripping the solvent from the reaction mixture, e.g., by distillation. Hydroxyalkylamides can be employed as surfactants in commercial products such as laundry detergents, as detergent agents for solubilizing plasma membranes and as thickeners.
EP 473 380 discloses a method of preparing solid hydroxyalkylamides by reacting alkyl esters with alkanolamines at controlled reaction temperatures, removing the alcohol (methanol) by-product, controlling the temperature of the reaction mixture to form a thick slurry, maintaining the slurry and recovering the solid hydroxyalkylamides.
U.S. Pat. No. 2,703,798 generally relates to processes of producing various detergents wherein an aliphatic ester of a fatty acid is reacted with an N-monoalkylglucamine. Aliphatic alcohol which is liberated as a product of the reaction is removed from the reaction vessel as it is formed.
WO 92/06070, WO 92/06071, WO 92/06072 and WO 92/06073 disclose processes for manufacturing linear glucamide surfactants by reacting an N-alkylglucamine and a fatty acid ester in the presence of a catalyst.